Exhaust system for motor bikes



' July 8, 1969 I B|ESECKER 3,453,824

EXHAUST SYSTEM FOR MOTOR BIKES Filed Nov 20, 1967 INVENTOR. I H6. 4 JOSEPH M.BIESECKER BY hl/ ATTORNEYS.

United States Patent 3,453,824 EXHAUST SYSTEM FOR MOTOR BIKES Joseph M. Biesecker, 1206 Hacienda Drive, Campbell, Calif. 95008 Filed Nov. 20, 1967, Ser. No. 684,169 Int. Cl. F02b 27/00 US. CI. 60-32 ABSTRACT OF THE DISCLOSURE An exhaust system for motor bikes constructed to give improved performance and efficiency for the motor bike engines of the two or four cylinder types. The exhaust pipe from each cylinder is provided with a straight section approximately two inches long connected to the cylinder. From these straight sections the pipes are curved to the rear and joined with a relatively small angle formed between the outlets thereof. These outlets are somewhat constricted and attached to the front of an expanding chamber. The exhaust gas fed by one of the pipes to the chamber produces a suction in the other of the pipes whereby the back pressure in the other pipe is decreased. This action alternates between the pipes.

This invention relates to an exhaust system for motor bikes having two or four cylinders.

An object of this invention is to provide an improved exhaust system for motor bikes for improving the efiiciency of the motor thereof, the exhaust system being constructed so that the resistance to the flow of the spent gases from the engine cylinders is reduced and the back pressure due to spent gases present in the exhaust pipes leading from the engine cylinders is also reduced.

Another object of this invention is to provide an improved exhaust system for motor bikes with two or four cylinders in which the exhaust pipes leading from the cylinders are each provided with a straight section of approximately two inches long connected directly to the cylinder and in which the pipes are then provided with a smooth curve leading to the rear of the motor bike where the exhaust pipes are attached to a connecting member, the outlet of which is welded to the small end of an expanding chamber, the connecting member having a bafile extending toward the inlet of the expanding chamber so that spent gas flowing from one of the exhaust pipes through the connecting member produces suction in the other of the pipes and draws out spent gas that may be lingering in the other of the pipes to reduce back pressure therein.

Other and further objects of this invention will be apparent to those skilled in the art to which it relates from the following specification, claims and drawing in which:

FIG. 1 is a side view of a motor bike provided with this improved exhaust system;

FIG. 2 is a fragmentary view of a part of the exhaust system showing exhaust pipes leading from the two cylinders joined to a connecting member which is attached to the small end of the expanding chamber;

FIG. 3 is a sectional view taken along the line 3-3 of FIG. 2; and

FIG. 4 is a longitudinal sectional view taken through the portion of the exhaust system shown in FIG. 2.

Referring to the drawing in detail, reference numerals and 11 designate the engine cylinders of a two-cylinder motor bike 12 which is of conventional construction. The engine cylinders 10 and 11 are provided with exhaust pipes 14 and 15, respectively, which are connected to the engine cylinders by conventional couplings 16 and 17, respectively. Exhaust pipes 14 and 15, which are of equal 3 Claims ice length, are provided with substantially straight sections 18 and 19, respectively, which are immediately adjacent to the cylinders 10 and 11, respectively. I have found that by making the sections 18 and 19 straight for a length of about two inches improved efiiciency and engine performance results so that increased mileage is obtained from the motor bike fuel. The reason for this, I believe, lies in the fact that these straight portions provide reduced resistance to the outward flow of the spent gases from the engine cylinders. The flow of the spent gases from the engine cylinders is also facilitated by the configuration of the connecting member 20 and the expanding chamber 21. The exhaust pipes 14 and 15 are attached by welding to the connecting member 20 which is attached to the small inlet of the expanding chamber 21, the large end of which is open to the atmosphere so that the exhaust gases flow out thereof.

The connecting member 20 is made by sawing a triangular section out of the middle part of a piece of pipe and thereafter bending the pipe so that the parts 22 and 23 are substantially parallel. The sawed edges are then abutting at 24 and welded as shown in FIGS. 2, 3 and 4. Thereafter a part of the bend is sawed olf leaving the opening 26 as shown in FIG. 3. The opening 26 of connecting member 20 is joined to the small end of the expanding chamber 21 by the Weld 25. The welded joint 24 between the sections 22 and 23 of connecting member 20 also provides a baflle 24a extending toward the inlet of expanding chamber 21. Expanding chamber 21 functions to suck the spent gases out of the pipes 22 and 23 through the outlet openings of these latter pipes past the baflle 24a. Thus, when the expanding chamber 21 is drawing spent gases out of pipe 22, for example, this action provides a suction in pipe 23 so that any spent gases in pipe 23 are sucked out. As a result, when exhaust gas is fed into the exhaust pipe 15 from cylinder 11, the back pressure in this pipe is reduced. The same is of course also true in the case of the exhaust pipe 14 from which the exhaust gases are sucked out by the action of expanding chamber 21 drawing spent gases out of pipes 15 and 23. I have found that the angle of approach between each of the pipes 22 and 23 and the inlet of pipe 21 should be relatively small and preferably less than 30 degrees and that these pipes should be substantially parallel with the outlets thereof curved toward each other at this relatively small angle, as shown in FIG. 4. This angle is measured on each side of the center line defined by the baflle 2411. These angles are determined by the tangents to the curved surfaces of pipes 22 and 23 which direct the exhaust gases into the inlet of pipe 21 past the baflle 24a. The angle of the cone formed by the expanding chamber 21 is also relatively small and does not exceed 30 degrees.

What I claim is:

1. In an exhaust system for motor bikes employing motors with at least two cylinders, the combination comprising exhaust pipes attached to the front sides of the motor cylinders, each of said pipes communicating with inside of a different one of said cylinders, the inlet end portions of each of the exhaust pipes having a substantially straight portion of predetermined length immedi channels connected to said exhaust pipes and having inwardly curved walls attached to the inlet of said expanding chamber, said connecting means also having a baffie extending toward the inlet of said expanding chamber so thatexhaust gas passing through one of said channels past said bafile into said expanding chamber produces suction in the other of said channels.

2. In an exhaust system for motor bikes employing motors with at least two cylinders, the combination as set forth in claim 1 further characterized in that said connecting means comprises a single length of pipe which is shaped so that the opposite end portions thereof form said substantially parallel channels and said inwardly curved walls comprise parts of the mid-portion of said pipe, said mid-portion having a part thereof cut away to form an opening attached to the inlet of said expanding chamber.

3. In an exhaust system for motor bikes employing motors With at least two cylinders, the combination as set forth in claim 2 further characterized in that said bafile References Cited UNITED STATES PATENTS 2/1957 Warren ISO-33 7/1958 Whitcomb 60-3-2 FOREIGN PATENTS 363,382 12/1931 Great Britain. 678,119 12/1929 France.

CARLTON R. CROYLE, Primary Examiner.

DOUGLAS HART, Assistant Examiner.

US. Cl. X.R. 

